I've twice toured in Poland both as part of longer largely unplanned multi-month tours. Once in 2014 from the Lithuanian border to Germany sticking mostly near the Baltic coast, and then in 2018 from the Czech Republic to the Lithuanian border.
My strategy was to avoid big cities as much as possible, which was reinforced after I rode through Łódź.
Everything seemed very cheap, and not only because my 2014 tour had included lots of Scandinavia.
Most of the time I was camping, often in campsites whose name was just a number - I assume this was a leftover from pre-1990.
When I couldn't find a campsite hotels were very cheap. Two incidents stand out.
Hotel 1: I asked at reception if there was a room for that night. The receptionist looked doubtful. "Only our most expensive room". It was, I think 120 złoty (about £25 I think) and about the most luxurious hotel room I've ever stayed in.
Hotel 2, on a very hot day: the price of a room was, I was told 110 złoty, but there was a 'special offer' of 90 złoty, because there was no hot water.
If you want to improve your Polish, I came across plenty of places where no English was spoken. In the holiday areas of the north, next to the coast and especially in the Masurian Lake district, German was the second language (reflecting no doubt the majority of non-Polish tourists). Elsewhere I often found myself shopping in small village skleps, where the customer has to tell the shopkeeper what they want and they fetch it from the shelf behind them (like Open All Hours). Pointing only gets you so far, and often the ever-increasing queue behind me came to my help, giving suggestions to the shopkeeper as to what I wanted. Invariably much hilarity ensued.
Apart from Łódź it was very pleasant cycling.
From time to time I unexpectedly came across stark reminders of 20th century history: a huge was cemetery at Lambinowice; a memorial to hundreds of Poles from a village deported post-1945 and never seen again; and an odd concrete road (like a Belgian one) which led to the village of Treblinka. Not that such experiences are unique to Poland - just what I recall from my trips.
I'll add anything else which occurs to me.